I was in the Navy. Your dad is wearing "Seafarers," which were more stylish uniforms than the straight issue. You can see the difference between his tapered bell-bottoms and the straight-legged ones on the guy at the top right.

Free GG - Thanks for the comment! It's no surprise; I know Dad had a lot of his Navy attire custom tailored. He recently told me a story of how his bag was stolen with one of his new custom tailored uniforms inside.